EUREKA, Calif. -- A California woman whose infant son died after ingesting methamphetamine-laced breast milk has been sentenced to six years in prison.

Maggie Jean Wortman, of Humboldt County, Calif., pleaded guilty last month to voluntary manslaughter as part of a deal with prosecutors, who had said they'd otherwise pursue a murder charge.

An autopsy on 6-week-old Michael Acosta III found that the baby died of "methamphetamine toxicity" on Nov. 21, 2010. Prosecutors say Wortman should have known the dangers of breastfeeding her child after using the drug.

But Judge Bruce Watson referred to a probation report that said Wortman has not fully taken responsibility for her son's death.